Hasil untuk "Metropolitan areas"

V. Ostrom, Charles M. Tiebout, R. Warren

Karolina Dziwulska, Christopher Spiess, Sarika Mishra et al.

Quantum communication technologies capable of operating reliably across heterogeneous optical channels are essential for scalable metropolitan quantum networks. Here we demonstrate high-dimensional time-bin-encoded quantum key distribution over a hybrid metropolitan link comprising 1.7 km free-space transmission and 685 m of optical fiber. Operating at a clock rate of 500 MHz in the C-band, we implement both 2- and 4-dimensional protocols, and obtain estimated secure finite-key rates of (95 +- 28) kbit/s for 4D at (25.0 +- 2.0) dB loss and (59 +- 27) kbit/s for 2D at (23.5 +- 2.3) dB loss. Crucially, we achieve continuous operation over 48 h in a fully self-referenced architecture: initial synchronization, interferometric phase stabilization, and long-term drift compensation are performed exclusively using the detected quantum signals, without auxiliary optical reference channels. Our results thus establish a practical and versatile platform for hybrid free-space-to-fiber quantum communication and show that the encoding dimensionality can be adapted to the optimal operating regime of realistic metropolitan channels, providing a pathway toward efficient, autonomous and deployable quantum network nodes.

N. Garcia-Chan, L. J. Alvarez-Vazquez, A. Martinez et al.

In this paper, a useful reinterpretation of the city as a porous medium justifies the application of well-known models on fluid dynamics to develop a multi-model study of urban air pollution due to traffic flow in a large city. Thus, to simulate the traffic flow through the city we use a nonconservative macroscopic traffic model combining the continuity equation with the Darcy-Brinkman-Forchheimer equations. For the air flow, regarding the emission rate of CO$_2$ and its dispersion in the atmosphere, we combine a microscopic model -- based on regression techniques but depending on vehicles' velocity and acceleration -- with a classical convection-diffusion-reaction transport model. To solve numerically above PDEs models, the finite element method of Lagrange $\rm{P_1}$ type along with suitable time marching schemes (like the strong stability preserving scheme) were sufficient to obtain stable numerical solutions. Several computational tests were run on a realistic scenario inspired by the Metropolitan Area of Guadalajara (Mexico), showing not only the influence of the urban landscape (that is, the porosity) on traffic flow, air flow, and pollution transport, but also other interesting phenomena such as rarefaction traffic waves.

Pouya Firouzmakan, Suprakash Datta

Vehicular Ad-hoc Networks (VANETs), a subclass of Mobile Ad-hoc Networks (MANETs), are expected to play a crucial role in the future of intelligent transportation systems (ITSs). A key objective of VANETs is to enable efficient and cost-effective communication among vehicles while supporting a large number of network participants and minimizing infrastructure dependency. However, the highly dynamic nature of vehicular networks poses significant challenges to their deployment. Clustering techniques are employed to address these challenges, with a strong emphasis on stability, as they directly influence the routing process and enhance the quality of service (QoS). This paper explores the feasibility of reducing reliance on roadside units (RSUs) in metropolitan areas while improving cluster stability. We propose an efficient clustering algorithm tailored for urban environments, leveraging existing metropolitan infrastructure to compensate for the absence of RSUs. Our approach designates public transportation buses as primary cluster heads (CHs), minimizing reliance on additional infrastructure, while stand-alone vehicles (SAVs) dynamically select additional CHs. Through comprehensive case studies and comparative analysis with existing algorithms, our results demonstrate the superior performance of the proposed method across different transmission ranges (TRs).

Mohammed K. Alqedra, Samuel Gyger, Katharina D. Zeuner et al.

The precise synchronization of distant clocks is a fundamental requirement for a wide range of applications. Here, we experimentally demonstrate a novel approach of quantum clock synchronization utilizing entangled and correlated photon pairs generated by a quantum dot at telecom wavelength. By distributing these entangled photons through a metropolitan fiber network in the Stockholm area and measuring the remote correlations, we achieve a synchronization accuracy of tens of picoseconds by leveraging the tight time correlation between the entangled photons. We show that our synchronization scheme is secure against spoofing attacks by performing a remote quantum state tomography to verify the origin of the entangled photons. We measured a distributed maximum entanglement fidelity of $0.817 \pm 0.040$ to the $|Φ^+\rangle$ Bell state and a concurrence of $0.660 \pm 0.086$. These results highlight the potential of quantum dot-generated entangled pairs as a shared resource for secure time synchronization and quantum key distribution in real-world quantum networks.

Mulugeta Girma, Zelalem Mulatu

Corridor development refers to the strategic planning, building, and operation of transportation infrastructure that connects key metropolitan areas within a city. This study aims to assess the effects of corridor development initiatives in Addis Ababa. Data were collected through on-site observations and interviews with key informants from relevant offices, alongside secondary data. Thematic analysis was employed to interpret the data. The study’s findings indicate that corridor development initiatives have decreased traffic congestion, enhanced pedestrian and bicycle access, and improved mobility, making commuting more enjoyable and efficient. Furthermore, it promotes sustainability through improving green spaces, open public areas, and non-motorized transportation infrastructure. Overall, the study found that the corridor development project has significantly boosted the city’s image. Finally, the study recommends using Addis Ababa’s corridor development as a model for urban planning and financial investment in transportation infrastructure, which can enhance the city’s quality of life. Besides, to address the city’s mobility challenges and promote a smart city, the study advocates for implementing integrated transit systems, vehicle sharing, traffic calming measures, and parking fees as part of the city’s ongoing development efforts.

Charlie Campanella, Rob van der Goot

Large language models (LLMs) have emerged as a useful technology for job matching, for both candidates and employers. Job matching is often based on a particular geographic location, such as a city or region. However, LLMs have known biases, commonly derived from their training data. In this work, we aim to quantify the metropolitan size bias encoded within large language models, evaluating zero-shot salary, employer presence, and commute duration predictions in 384 of the United States' metropolitan regions. Across all benchmarks, we observe negative correlations between the metropolitan size and the performance of the LLMS, indicating that smaller regions are indeed underrepresented. More concretely, the smallest 10 metropolitan regions show upwards of 300% worse benchmark performance than the largest 10.

Artur Grigorev, Sajjad Shafiei, Hanna Grzybowska et al.

This research presents a comprehensive approach to predicting the duration of traffic incidents and classifying them as short-term or long-term across the Sydney Metropolitan Area. Leveraging a dataset that encompasses detailed records of traffic incidents, road network characteristics, and socio-economic indicators, we train and evaluate a variety of advanced machine learning models including Gradient Boosted Decision Trees (GBDT), Random Forest, LightGBM, and XGBoost. The models are assessed using Root Mean Square Error (RMSE) for regression tasks and F1 score for classification tasks. Our experimental results demonstrate that XGBoost and LightGBM outperform conventional models with XGBoost achieving the lowest RMSE of 33.7 for predicting incident duration and highest classification F1 score of 0.62 for a 30-minute duration threshold. For classification, the 30-minute threshold balances performance with 70.84% short-term duration classification accuracy and 62.72% long-term duration classification accuracy. Feature importance analysis, employing both tree split counts and SHAP values, identifies the number of affected lanes, traffic volume, and types of primary and secondary vehicles as the most influential features. The proposed methodology not only achieves high predictive accuracy but also provides stakeholders with vital insights into factors contributing to incident durations. These insights enable more informed decision-making for traffic management and response strategies. The code is available by the link: https://github.com/Future-Mobility-Lab/SydneyIncidents

Saad Mohammad Abrar, Kazi Tasnim Zinat, Naman Awasthi et al.

Early in the pandemic, counties and states implemented a variety of non-pharmacological interventions (NPIs) focused on mobility, such as national lockdowns or work-from-home strategies, as it became clear that restricting movement was essential to containing the epidemic. Due to these restrictions, businesses were severely affected and in particular, small, urban restaurant businesses. In addition to that, COVID-19 has also amplified many of the socioeconomic disparities and systemic racial inequities that exist in our society. The overarching objective of this study was to examine the changes in small urban restaurant visitation patterns following the COVID-19 pandemic and associated mobility restrictions, as well as to uncover potential disparities across different racial/ethnic groups in order to understand inequities in the impact and recovery. Specifically, the two key objectives were: 1) to analyze the overall changes in restaurant visitation patterns in US metropolitan areas during the pandemic compared to a pre-pandemic baseline, and 2) to investigate differences in visitation pattern changes across Census Block Groups with majority Asian, Black, Hispanic, White, and American Indian populations, identifying any disproportionate effects. Using aggregated geolocated cell phone data from SafeGraph, we document the overall changes in small urban restaurant businesses' visitation patterns with respect to racial composition at a granularity of Census Block Groups. Our results show clear indications of reduced visitation patterns after the pandemic, with slow recoveries. Via visualizations and statistical analyses, we show that reductions in visitation patterns were the highest for small urban restaurant businesses in majority Asian neighborhoods.

Mats Gustafsson

The number of degrees of freedom (NDoF) in a communication channel fundamentally limits the number of independent spatial modes available for transmitting and receiving information. Although the NDoF can be computed numerically for specific configurations using singular value decomposition (SVD) of the channel operator, this approach provides limited physical insight. In this paper, we introduce a simple analytical estimate for the NDoF between arbitrarily shaped transmitter and receiver regions in free space. In the electrically large limit, where the NDoF is high, it is well approximated by the mutual shadow area, measured in units of wavelength squared. This area corresponds to the projected overlap of the regions, integrated over all lines of sight, and captures their effective spatial coupling. The proposed estimate generalizes and unifies several previously established results, including those based on Weyl's law, shadow area, and the paraxial approximation. We analyze several example configurations to illustrate the accuracy of the estimate and validate it through comparisons with numerical SVD computations of the propagation channel. The results provide both practical tools and physical insight for the design and analysis of high-capacity communication and sensing systems.

Kostecki Robert

The main aim of this paper is to introduce a solution for network analysis based on pgRouting to resolve the bicycle accessibility of forested green spaces. The proposed application uses open-source software tools such as PostgreSQL with PostGIS extension. The solution includes a complete description of how to perform network analysis using a spatial database with SQL and pgRouting. The implemented functionalities consist of solutions for finding the equidistance or isochrone area for any selected point location. The method is tested on case study data drawn from a total of 9,500 km of roads suitable for cyclists in the Poznań Metropolitan Area, located in western Poland. The results of the analysis were isochrones determining the bicycle accessibility of forested areas. The accessibility analysis was performed considering an urbanised residential area. As a result of the analysis, locations with the best and limited access to forested green areas were identified. Moreover, the described methodology is ready to be used to solve various accessibility problems.

Asma Mehan, Sina Mostafavi

This research project and exhibit, delves into the complex relationship between public exhibition, urban spaces, and socio-political norms in shaping urban thresholds within the two American and European metropolitan cities of Houston and Amsterdam. This study also investigates the transformative power of new media and emerging technologies in the production, circulation, and consumption of design, offering fresh perspectives on the influence of these technologies on urban design studies and digitally augmented physical spaces. By merging interdisciplinary research areas, including Design Computation and Fabrication, Urban Communities, and Spatial Justice, this project provides an immersive exploration into the co-production of liminal spaces, focusing on the participation of diverse publics and the dynamics of inclusion, exclusion, and recognition in two cities of Houston and Amsterdam. The main emphasis of this paper is on the critical urban studies and the role of emerging technologies in advancing the theoretical and methodological frameworks of the presented immersive installation project.

Luyi Qiu

Coordination development across various subsystems, particularly economic, social, cultural, and human resources subsystems, is a key aspect of urban sustainability that has a direct impact on the quality of urbanization. Hangzhou Metropolitan Circle composing Hangzhou, Huzhou, Jiaxing, Shaoxing, was the first metropolitan circle approved by National Development and Reform Commission (NDRC) as a demonstration of economic transformation. To evaluate the coupling degree of the four cities and to analyze the coordinative development in the three systems (Digital Economy System, Regional Innovation System, and Talent Employment System), panel data of these four cities during the period 2015-2022 were collected. The development level of these three systems were evaluated using standard deviation and comprehensive development index evaluation. The results are as follows: (1) the coupling coordination degree of the four cities in Hangzhou Metropolitan Circle has significant regional differences, with Hangzhou being a leader while Huzhou, Jiaxing, Shaoxing have shown steady but slow progress in the coupling development of the three systems; and (2) the development of digital economy and talent employment are the breakthrough points for construction in Huzhou, Jiaxing, Shaoxing. Related suggestions are made based on the coupling coordination results of the Hangzhou Metropolitan Circle.

M. Di Martino, P. Linke, E. N. Pistikopoulos

The energy-water demands of metropolitan regions and agricultural ecosystems are ever-increasing. To tackle this challenge efficiently and sustainably, the interdependence of these interconnected resources has to be considered. In this work, we present a holistic decision-making framework which takes into account simultaneously a water and energy supply system with the capability of satisfying metropolitan and agricultural resource demands. The framework features: (i) a generic large-scale planning and scheduling optimization model to minimize the annualized cost of the design and operation of the energy-water supply system, (ii) a mixed-integer linear optimization formulation, which relies on the development of surrogate models based on feedforward artificial neural networks and first-order Taylor expansions, and (iii) constraints for land and water utilization enabling multi-objective optimization. The framework provides the operational profiles of all energy-water system elements over a given time horizon, which uncover potential synergies between the essential food, energy, and water resource supply systems.

Mariangela Cerullo, Paolo Izzo

This paper presents the results of an intensive research on the phenomenon of split intransitivity in Campanian varieties. In the first part it presents the phenomenon according to the different theoretical approaches considered, in order to analyse the considerable amount of data presented in the following sections. The second part is devoted to the central Campanian varieties, in which the data from the metropolitan area of Naples, Salerno and the hinterland are exposed. The peculiarity of the Acerno variety, which is more isolated than the others, leads to present the data of this variety separately. The last part presents the data from the south of the region, the Cilento, divided into two different areas, which are very different from a sociolinguistic point of view. For each dialectal area, an attempt is made to identify the internal parameters that characterise the variation in the choice of the auxiliary and, where necessary, the authors recourse to sociolinguistic variation or contact among different varieties that may have had an influence on the phenomenon.

Taquan Ma, Rui Liu, Zheng Li et al.

In the context of promoting high-quality development of mountainous urban areas, it is of great significance to explore the evolutionary trajectory of habitat quality in the future based on policy-driven backgrounds, particularly for the protection of the Western mountainous ecosystem. This study takes the Chongqing metropolitan area, a typical southwestern mountainous city, as the study area. Based on land use data from 1990 to 2020, the study combines the InVEST and PLUS models, considering the constraints imposed by urban construction planning and ecological control policies, to investigate the spatiotemporal variations of habitat quality from 1990 to 2030. The findings are as follows: (1) From 1990 to 2020, there was a significant decrease in cultivated land area in the study area, while forestland and unused land showed a declining trend. Conversely, built-up land, grassland, and water bodies exhibited an increasing trend. In the land use simulation for 2030, under the scenarios of natural growth and ecological protection, the cultivated land area further decreased, while forestland and grassland received a certain degree of protection. In the scenario of development, a large amount of cultivated land was converted into built-up land. (2) From 1990 to 2030, significant overall habitat quality changes were observed among different regions within the study area. Except for Nanchuan District and Qijiang District, other administrative regions experienced a certain degree of decline in habitat quality. The distribution of habitat quality exhibited significant spatial heterogeneity. The low-value habitat areas were centered in the middle of the metropolitan area and gradually expanded outward. The high-value habitat areas were concentrated in the study area, including the Huaying Mountain range and other mountainous ecological corridor regions. (3) Habitat quality in the study area showed a decreasing trend with an increasing slope gradient. With the development of urbanization, habitat quality degradation gradually spread to high-altitude and steep-slope areas. (4) The expansion of built-up land is the main cause of habitat degradation in the study area. From 1990 to 2030, against the background of development strategies in the study area, the expansion of built-up land encroached upon cultivated land and forestland. In the habitat quality prediction for 2030, habitat degradation in the region will continue to intensify. This study provides scientific references and the basis for promoting regional sustainable land use and ecological conservation.

Léia Sousa de Sousa, André Costa Drummond

Metropolitan optical networks are undergoing major transformations to continue being able to provide services that meet the requirements of the applications of the future. The arrival of the $5G$ will expand the possibilities for offering IoT applications, autonomous vehicles, and smart cities services while imposing strong pressure on the physical infrastructure currently implemented, as well as on static traffic engineering techniques that do not respond in an agile way to the dynamic and heterogeneous nature of the upcoming traffic patterns. In order to guarantee the strictest quality of service and quality of experience requirements for users, as well as meeting the providers' objectives of maintaining an acceptable trade-off between cost and performance, new architectures for metropolitan optical networks have been proposed in the literature, with a growing interest starting from $2017$. However, due to the proliferation of a dozen of new architectures in recent years, many questions need to be investigated regarding the planning, implementation, and management of these architectures, before they could be considered for practical application. This work presents a comprehensive survey of the new proposed architectures for metropolitan optical networks. Firstly, the main data transmission systems, equipment involved, and the structural organization of the new metro ecosystems are discussed. The already established and the novel architectures are presented, highlighting its characteristics and application, and comparative analysis among these architectures is carried out identifying the future technological trends. Finally, outstanding research questions are drawn to help direct future research on the field.

Zipei Fan, Xiaojie Yang, Wei Yuan et al.

Knowing "what is happening" and "what will happen" of the mobility in a city is the building block of a data-driven smart city system. In recent years, mobility digital twin that makes a virtual replication of human mobility and predicting or simulating the fine-grained movements of the subjects in a virtual space at a metropolitan scale in near real-time has shown its great potential in modern urban intelligent systems. However, few studies have provided practical solutions. The main difficulties are four-folds. 1) The daily variation of human mobility is hard to model and predict; 2) the transportation network enforces a complex constraints on human mobility; 3) generating a rational fine-grained human trajectory is challenging for existing machine learning models; and 4) making a fine-grained prediction incurs high computational costs, which is challenging for an online system. Bearing these difficulties in mind, in this paper we propose a two-stage human mobility predictor that stratifies the coarse and fine-grained level predictions. In the first stage, to encode the daily variation of human mobility at a metropolitan level, we automatically extract citywide mobility trends as crowd contexts and predict long-term and long-distance movements at a coarse level. In the second stage, the coarse predictions are resolved to a fine-grained level via a probabilistic trajectory retrieval method, which offloads most of the heavy computations to the offline phase. We tested our method using a real-world mobile phone GPS dataset in the Kanto area in Japan, and achieved good prediction accuracy and a time efficiency of about 2 min in predicting future 1h movements of about 220K mobile phone users on a single machine to support more higher-level analysis of mobility prediction.

He-in Cheong, Jonathan Sanz Carcelen, Manlika Sukitpaneenit et al.

Passenger rejection by taxi drivers impacts the travel behaviour in many cities and suburban areas, often leaving those potential customers in non-popular zones stranded without access to taxis. To overcome this problem, many practices have been implemented, such as penalties to drivers, bans, and new pricing strategies. This paper presents a double auction taxi fare scheme, which gives both passengers and taxi drivers to influence the price, coupled with a clustering method to discourage strategic service rejection in the case study of Bangkok Metropolitan Region, Thailand, which has detailed data availability and uneven taxi journey distributions. The double auction mechanism is tailored to 2019 taxi trips, service rejection complaints, and local travel behaviour to boost transportation equity. To benchmark the performance of the new double auction scheme, a bespoke agent-based model of the taxi service in Bangkok Metropolitan Region at different rejection rates of 0%-20% was created. On one hand, the current rejection behaviour was modelled, and on the other, the double auction pricing strategy was applied. The results indicate that the double auction strategy generates a spatially distributed accessibility and leads to a higher taxi assignment success rate by up to 30%. The double auction scheme increases pickups from locations that are 20-40 km from central Bangkok by 10-15%, despite being areas of low profit. Due to the changing taxi travel landscape and longer taxi journeys, the total air pollutant emissions from the taxis increase by 10% while decreasing local emissions within central areas of Bangkok by upto 40%. Using a 5 Baht average surcharge, the total revenue drops by 20%. The results show that an equity-driven pricing strategy as an implementation of transport policy would be beneficial.

Yanmei LI

South Florida has been among the top foreclosure markets in the United States, but little research has explored whether this market presents different dynamics compared to other metropolitan areas. This research chooses Broward County to explore whether socioeconomic characteristics and certain public policy instruments relate to subprime lending and mortgage foreclosure patterns. Results indicate areas bounded by linear highways and railroads have a concentration of low-income black population and subprime loans. The spatial distribution of subprime loans is mostly explained by a higher percentage of minority and/or Hispanic population in a neighborhood. Yet, racial minorities, instead of Hispanic origin, contributes mostly to the concentration of subprime loans. The spatial pattern of foreclosures is more complex, determined not only by subprime loans but also possibly other factors associated with the mortgage crisis. This suggests that disadvantaged neighborhoods are disproportionally lacking favorable opportunities due to institutional and sub- cultural forces shaping the geography of subprime and foreclosure.